Ethylene interpolymerizations

Abstract

Processes for polymerizing ethylene/α-olefin interpolymer compositions are disclosed. The interpolymer compositions have a controlled composition and a controlled molecular weight distribution. The processes utilize a highly-efficient homogeneous catalyst composition in at least one reactor to produce a first interpolymer having a narrow composition distribution and a narrow molecular weight distribution, and a highly-efficient heterogeneous Ziegler catalyst in at least one other reactor. The reactors can be operated sequentially or separately, depending upon the desired product. The novel compositions have good optical properties (e.g., clarity and haze) and good physical properties (e.g., modulus, yield strength, toughness and tear). Useful products which can be formed from these compositions include film, molded articles and fiber.

We claim: 
     
       1. A process for preparing an ethylene/α-olefin interpolymer composition, comprising the steps of: (A) reacting by contacting ethylene and at least one other α-olefin under solution polymerization conditions in the presence of an unsupported homogeneous monocyclopentadienyl transition metal catalyst composition in at least one reactor to produce a solution of a first interpolymer which has less than or equal to about 250 ppm of aluminum residue, a composition distribution breadth index (CDBI), defined as the weight percent of the polymer molecules having a comonomer content within 50 percent of the median total molar comonomer content of greater than about 50 percent, a degree of branching less than or equal to 2 methyls/1000 carbons in about 15 percent (by weight) or less of the first interpolymer, and a narrow molecular weight distribution,   (B) reacting by contacting ethylene and at least one other α-olefin under solution polymerization conditions and at a higher polymerization reaction temperature than used in step (A) in the presence of a heterogeneous Ziegler catalyst in at least one other reactor to produce a solution of a second interpolymer which has a degree of branching less than or equal to 2 methyls/1000 carbons in about 10 percent (by weight) or more, and a degree of branching equal to or greater than 25 methyls/1000 carbons in about 25 percent (by weight) or less of the second interpolymer, and a broad molecular weight distribution, wherein the Ziegler catalyst comprises (i) a solid support component derived from a magnesium halide or silica, and   (ii) a transition metal component represented by the formulas: TrX' 4-q  (OR 1 ) q , TrX' 4-q  R 2   q , VOX'3 and VO (OR 1 ) 3 , wherein: Tr is a Group IVB, VB, or VIB metal,   q is 0 or a number equal to or less than 4,   X' is a halogen, and   R 1  is an alkyl group, aryl group or cycloalkyl group having from 1 to 20 carbon atoms, and   R 2  is an alkyl group, aryl group, aralkyl group, or substituted aralkyl group, and       (C) combining the solution of the first interpolymer with the solution of the second interpolymer to form a high temperature polymer solution comprising the ethylene/α-olefin interpolymer composition, and   (D) removing the solvent from the polymer solution of step (C) and recovering the ethylene/α-olefin interpolymer composition.   
     
     
       2. The ethylene/α-olefin interpolymer composition produced by the process of claim 1. 
     
     
       3. The process of claim 1 wherein the α-olefinin in each of steps (A) and (B) is 1-octene. 
     
     
       4. The ethylene/1-octene interpolymer composition produced by the process of claim 3. 
     
     
       5. The process of claim 1 wherein the homogeneous catalyst composition comprises a metal coordination complex comprising a metal of group 4 of the Periodic Table of the Elements and a delocalized π-bonded moiety substituted with a constrain-inducing moiety, said complex having a constrained geometry about the metal atom such that the angle at the metal between the centroid of the delocalized, substituted π-bonded moiety and the center of at least one remaining substituent is less than such angle in a similar complex containing a similar π-bonded moiety lacking in such constraininducing substituent, and provided further that for such complexes comprising more than one delocalized, substituted π-bonded moiety, only one thereof for each metal atom of the complex is a cyclic, delocalized, substituted π-bonded moiety. 
     
     
       6. The process of claim 5 wherein the homogeneous catalyst composition further comprises an activating cocatalyst. 
     
     
       7. The process of claim 5 wherein the metal coordination complex corresponds to the formula: ##STR9## wherein: M is a metal of group 4 of the Periodic Table of the Elements; Cp* is a cyclopentadienyl or substituted cyclopentadienyl group bound in an η 5  bonding mode to M;   Z is a moiety comprising boron, or a member of group 14 of the Periodic Table of the Elements, and optionally sulfur or oxygen, said moiety having up to 20 non-hydrogen atoms, and optionally Cp* and Z together form a fused ring system;   X independently each occurrence is an anionic ligand group having up to 30 non-hydrogen atoms;   n is 1 or 2; and   Y is an anionic or nonanionic ligand group bonded to Z and M comprising nitrogen, phosphorus, oxygen or sulfur and having up to 20 non-hydrogen atoms, optionally Y and Z together form a fused ring system.   
     
     
       8. The process of claim 5 wherein the metal coordination complex corresponds to the formula: ##STR10## wherein: R' each occurrence is independently selected from the group consisting of hydrogen, alkyl, aryl, and silyl, and combinations thereof having up to 20 non-hydrogen atoms; X each occurrence independently is selected from the group consisting of hydride, halo, alkyl, aryl, silyl, aryloxy, alkoxy, amide, siloxy and combinations thereof having up to 20 non-hydrogen atoms;   Y is --O--, --S--, --NR*--, --PR*--, or a neutral two electron donor ligand selected from the group consisting of OR*, SR*, NR* 2  or PR* 2  ;   M is a metal of group 4 of the Periodic Table of the Elements; and   Z is SiR* 2 , CR* 2 , SiR* 2  SiR* 2 , CR* 2  CR* 2 , CR*═CR*, CR* 2  SiR* 2 , BR*; wherein R* each occurrence is independently selected from the group consisting of hydrogen, alkyl, aryl, silyl, halogenated alkyl, halogenated aryl groups having up to 20 non-hydrogen atoms, and mixtures thereof, or two or more R* groups from Y, Z, or both Y and Z form a fused ring system; and n is 1 or 2.     
     
     
       9. The process of claim 5 wherein the metal coordination complex is an amidosilane- or amidoalkanediyl-compound corresponding to the formula: ##STR11## wherein: M is titanium, zirconium or hafnium, bound in an η 5  bonding mode to the cydopentadienyl group; R' each occurrence is independently selected from the group consisting of hydrogen, alkyl and aryl and combinations thereof having up to 7 carbon atoms, or silyl;   E is silicon or carbon;   X independently each occurrence is hydride, halo, alkyl, aryl, aryloxy or alkoxy of up to 10 carbons, or silyl;   m is 1 or 2; and   n is 1 or 2.   
     
     
       10. The process of claim 5 wherein the metal coordination complex is an ionic catalyst having a limiting charge separated structure corresponding to the formula: ##STR12## wherein: M is a metal of group 4 of the Periodic Table of the Elements; Cp* is a cyclopentadienyl or substituted cyclopentadienyl group bound in an η 5  bonding mode to M;   Z is a moiety comprising boron, or a member of group 14 of the Periodic Table of the Elements, and optionally sulfur or oxygen, said moiety having up to 20 non-hydrogen atoms, and optionally Cp* and Z together form a fused ring system;   X independently each occurrence is an anionic ligand group having up to 30 non-hydrogen atoms;   n is 1 or 2; and   XA* -   is  -  X(B(C 6  F 5 ) 3 ).   
     
     
       11. The process of claim 1 wherein the homogeneous catalyst composition has a reactivity ratio less than half that of the heterogeneous catalyst. 
     
     
       12. A process for preparing an ethylene/α-olefin interpolymer composition, comprising the steps of: (A) polymerizing ethylene and at least one other α-olefin in a solution process under suitable solution polymerization temperatures and pressures in at least one reactor containing an unsupported homogeneous monocyclopentadienyl transition metal catalyst composition to produce a first interpolymer solution comprising a first interpolymer having less than or equal to about 250 ppm of aluminum residue, a composition distribution breadth index (CDBI), defined as the weight percent of the polymer molecules having a comonomer content within 50 percent of the median total molar comonomer content of greater than about 50 percent, a degree of branching less than or equal to 2 methyls/1000 carbons in about 15 percent (by weight) or less of the first interpolymer, and a narrow molecular weight distribution, and   (B) sequentially passing the interpolymer solution of (A) into at least one other reactor containing a heterogeneous Ziegler catalyst, ethylene and at least one other α-olefin under solution polymerization conditions and at a polymerization temperature higher than that used in (A), to form a high temperature polymer solution comprising the ethylene/α-olefin interpolymer composition, wherein the Ziegler catalyst comprises (i) a solid support component derived from a magnesium halide or silica, and   (ii) a transition metal component represented by the formulas: TrX' 4-q  (OR 1 ) q , TrX' 4-q  R 2   q , VOX'3 and VO (OR 1 ) 3 , wherein: Tr is a Group IVB, VB, or VIB metal,   q is 0 or a number equal to or less than 4,   X' is a halogen, and   R 1  is an alkyl group, aryl group or cycloalkyl group having from 1 to 20 carbon atoms, and   R 2  is an alkyl group, aryl group, aralkyl group, or substituted aralkyl group, and       (C) removing the solvent from the polymer solution of step (B) and recovering the ethylene/α-olefin interpolymer composition.   
     
     
       13. The ethylene/α-olefin interpolymer composition produced by the process of claim 12. 
     
     
       14. The process of claim 12 wherein the α-olefin is 1-octene. 
     
     
       15. The ethylene/1-octene interpolymer composition produced by the process of claim 14. 
     
     
       16. The process of claim 12 wherein the homogeneous catalyst composition comprises a metal coordination complex comprising a metal of group 4 of the Periodic Table of the Elements and a delocalized π-bonded moiety substituted with a constrain-inducing moiety, said complex having a constrained geometry about the metal atom such that the angle at the metal between the centroid of the delocalized, substituted π-bonded moiety and the center of at least one remaining substituent is less than such angle in a similar complex containing a similar π-bonded moiety lacking in such constrain-inducing substituent, and provided further that for such complexes comprising more than one delocalized, substituted π-bonded moiety, only one thereof for each metal atom of the complex is a cyclic, delocalized, substituted π-bonded moiety. 
     
     
       17. The process of claim 12 wherein the homogeneous catalyst composition further comprises an activating cocatalyst. 
     
     
       18. The process of claim 16 wherein the metal coordination complex corresponds to the formula: ##STR13## wherein: M is a metal of group 4 of the Periodic Table of the Elements; Cp* is a cyclopentadienyl or substituted cyclopentadienyl group bound in an η 5  bonding mode to M;   Z is a moiety comprising boron, or a member of group 14 of the Periodic Table of the Elements, and optionally sulfur or oxygen, said moiety having up to 20 non-hydrogen atoms, and optionally Cp* and Z together form a fused ring system;   X independently each occurrence is an anionic ligand group having up to 30 non-hydrogen atoms;   n is 1 or 2; and   Y is an anionic or nonanionic ligand group bonded to Z and M comprising nitrogen, phosphorus, oxygen or sulfur and having up to 20 non-hydrogen atoms, optionally Y and Z together form a fused ring system.   
     
     
       19. The process of claim 16 wherein the metal coordination complex corresponds to the formula: ##STR14## wherein: R' each occurrence is independently selected from the group consisting of hydrogen, alkyl, aryl, and silyl, and combinations thereof having up to 20 non-hydrogen atoms; X each occurrence independently is selected from the group consisting of hydride, halo, alkyl, aryl, silyl, aryloxy, alkoxy, amide, siloxy and combinations thereof having up to 20 non-hydrogen atoms;   Y is --O--, --S--, --NR*--, --PR*--, or a neutral two electron donor ligand selected from the group consisting of OR*, SR*, NR* 2  or PR* 2  ;   M is a metal of group 4 of the Periodic Table of the Elements; and   Z is SiR* 2 , CR* 2 , SiR* 2  SiR* 2 , CR* 2  CR* 2 , CR*═CR*, CR* 2  SiR* 2 , BR*; wherein R* each occurrence is independently selected from the group consisting of hydrogen, alkyl, aryl, silyl, halogenated alkyl, halogenated aryl groups having up to 20 non-hydrogen atoms, and mixtures thereof, or two or more R* groups from Y, Z, or both Y and Z form a fused ring system; and n is 1 or 2.     
     
     
       20. The process of claim 16 wherein the metal coordination complex is an amidosilane- or amidoalkanediyl-compound corresponding to the formula: ##STR15## wherein: M is titanium, zirconium or hafnium, bound in an η 5  bonding mode to the cyclopentadienyl group; R' each occurrence is independently selected from the group consisting of hydrogen, alkyl and aryl and combinations thereof having up to 7 carbon atoms, or silyl;   E is silicon or carbon;   X independently each occurrence is hydride, halo, alkyl, aryl, aryloxy or alkoxy of up to 10 carbons, or silyl;   m is 1 or 2; and   n is 1 or 2.   
     
     
       21. The process of claim 16 wherein the metal coordination complex is an ionic catalyst having a limiting charge separated structure corresponding to the formula: ##STR16## wherein: M is a metal of group 4 of the Periodic Table of the Elements; Cp* is a cyclopentadienyl or substituted cyclopentadienyl group bound in an η 5  bonding mode to M;   Z is a moiety comprising boron, or a member of group 14 of the Periodic Table of the Elements, and optionally sulfur or oxygen, said moiety having up to 20 non-hydrogen atoms, and optionally Cp* and Z together form a fused ring system;   X independently each occurrence is an anionic ligand group having up to 30 non-hydrogen atoms;   n is 1 or 2; and   XA* -   is  -  X(B(C 6  F 5 ) 3 ).   
     
     
       22. The process of claim 12 wherein the homogeneous catalyst composition has a reactivity ratio less than half that of the heterogeneous catalyst. 
     
     
       23. The process of claims 1 or 12 wherein the first interpolymer has long chain branching. 
     
     
       24. The process of claims 1 or 12 wherein the first interpolymer has from about 0.01 to about 3 long chain branches per 1000 carbons. 
     
     
       25. The process of claims 1 or 12 wherein the first interpolymer has a molecular weight distribution, M w  /M n , of less than about 3.5, and an I 10  /I 2  ratio and molecular weight distribution, M w  /M n , corresponding to the relationship: M w  /M n  ≦I 10  /I 2  -4.63. 
     
     
       26. The process of claims 1 or 12 wherein the first interpolymer has a critical shear stress at onset of gross melt fracture of greater than about 4×10 6  dyne/cm 2 . 
     
     
       27. The process of claims 1 or 12 wherein the first interpolymer has a critical shear rate at onset of surface melt fracture at least fifty percent greater than the critical shear rate at onset of surface melt fracture of a linear polymer having about the same M w  /M n  and I 2 .